Other analog computers for solving problems in science, engineering and mathematics are programmed using patch cords to connect computing component, such as adders, integrators and coefficient potentiometers. This patching is time-consuming and can lead to errors if one is not careful to place the patch plug in the right jack. In addition, patch cords usually are heavy, expensive and susceptable to discontinuities through wear and abuse, leading to programming errors. If, for example, a hundred shielded patch cords were used on a patch board to program a problem, they not only would add appreciable weight to the patch board but also their large number would contribute to patching errors and to time-consuming effort to debug any errors.
On the other hand, digital computers are programmed by means of punched cards, punched or magnetic tape and directly from a typewriter keyboard. This enables one to use the same deck of punched cards to repeat solutions of a problem on a computer. Thus far punched cards have not been used as an alternate or substitute method of programming an analog computer. In the proposed computer each punched hole in a card represents or performs the function of a patched cord. Thus, to perform the function of a one hundred patch cords, one would need to punch one hundred holes in a card. Then one would insert this card in a slot, turn on the computer and all of the desired components would be connected to each other instantly. This is of great advantage to a classroom mathematics, physics or electronics teacher. For example, say it is desirable to program several problems during a classroom period in order to illustrate graphically to a class the solutions to various types of problems. The teacher would bring to class as many prepunched cards as problems to be solved in class, plus the computer, which might be book-sized or a little larger. Each time a new problem is to be solved, the teacher replaces the old card with a new one, inserts one or two patch cords to complete the needed patching of the board and turns on the computer. As in digital computers, these cards can be used over and over again at different classes. However, instead of having a deck of perhaps several hundred cards as in digital computer programming, a single card is needed to program each problem.